If it's placed correctly, it really shouldn't.  We treat many thin skinned at our office with this product and Juvederm.  If it's placed too superficially in the dermis (the layer of skin that contains the cells that make collagen, collagen, elastic fibers, blood vessels, etc.), it could look slightly bluish or like a bruise that doesn't go away.  If it's placed unevenly, it could look lumpy.  Good offices will have the enzyme that dissolves it in stock, just in case there is ever a problem.  You might ask about this before you agree to a treatment!    Dr. I